1. Field of the Invention
The present invention relates to a ceramic element,
2. Related Background Art
Ceramic elements such as varistors, thermistors, and inductors are composed of a ceramic body having an internal electrode layer and ceramic layer, and an external electrode that is provided so as to be electrically connected to the internal electrode layer. Ceramic elements having the above structure are often fixed and connected by soldering the external electrode to a printed circuit board or the like. However, unmodified conventional external electrodes tend to melt from the solder heat and diffuse into the solder, which tends to result in poor connections. The solder heat resistance of external electrodes has conventionally been improved through a structure having a base electrode and a plating layer of Ni or the like formed on the surface thereof. In the interests of manufacturing costs and the like, such plating layers are generally formed by electroplating.
However, if the ceramic layer does not have enough insulation resistance, the plating layer may sometimes spread out of the area where the base electrode is to be formed (plating spread), or parts other than the base electrode may become plated (plating adhesion), during the electroplating process. These phenomena are considered problems which can cause external electrode shorts.
A method that has been developed to prevent such “plating spread” and “plating adhesion” during the electroplating process is to coat the surface of the ceramic body with a glass layer and oxide layer (or insulating layer) prior to the plating process (see JP-A 2007-242995).